1. Field of the Invention
The present invention is directed to an arrangement for the control of thread tension in a spool creel having several spool holders each provided with a brake rotor working with a braking element that is adjustable by a tensioning lever carrying a roller; wherein the roller and lever is biased by the departing thread to take up an angular position dependent upon thread tension and net weight.
Such arrangements which are presently in the marketplace have the advantage that the force exercised by the braking band automatically decreases as the wind diameter of each spool is reduced. The weight distribution on the tensioning lever is predetermined and thus also the thread tension exercised by the creel spools on the threads.
2. Description of Related Art
The creel arrangements presently on the marketplace (compare for example, DE OS 19 18 161) have the advantage that the braking force exercised by the braking arrangement is automatically decreased when the wind diameter on the spools is reduced. The weight distribution on the tensioning level is predetermined and thus also the thread tension exercised upon the threads taken from the creel.
From DE PS 88 3 727, it is known to provide electromagnetic brakes to all spool holders to drive all magnets in parallel switching and to alter the activation current by a common setting arrangement. In this way, the entire tension from the various creels can be changed during operation and, at switch-off, a rapid braking action can be obtained by raising the braking force. This gives rise however to a loss of individual control of the tension of the individual spools.
It is also known to provide pneumatic biasing arrangements to thread brakes (DE GM 80 25 217) in which the biasing for a plurality of thread brakes in a spool creel can be centrally set and controlled.
Swiss Patent 358 043 describes a thread brake in which a braking platelet acts upon the threads by means of a pneumatic cylinder piston assembly whose pressure is set from a central control point.
British Patent 1 071 190 discloses the provision of a brake shoe to a spool which under the influence of a pressure means, can be forced against a rotating braking surface.